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<h2><span class="refentrytitle">Struct template null_eval</span></h2>
<p>boost::proto::context::null_eval</p>
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<h2 class="refsynopsisdiv-title">Synopsis</h2>
<div class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../../proto/reference.html#header.boost.proto.context.null_hpp" title="Header &lt;boost/proto/context/null.hpp&gt;">boost/proto/context/null.hpp</a>&gt;

</span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">,</span> <span class="keyword">typename</span> Context<span class="special">&gt;</span> 
<span class="keyword">struct</span> <a class="link" href="null_eval.html" title="Struct template null_eval">null_eval</a> <span class="special">{</span>
  <span class="comment">// types</span>
  <span class="keyword">typedef</span> <span class="keyword">void</span> <a name="boost.proto.context.null_eval.result_type"></a><span class="identifier">result_type</span><span class="special">;</span>

  <span class="comment">// <a class="link" href="null_eval.html#id-1_3_32_5_56_2_1_1_1_3-bb">public member functions</a></span>
  <span class="keyword">void</span> <a class="link" href="null_eval.html#id-1_3_32_5_56_2_1_1_1_3_1-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">Expr</span> <span class="special">&amp;</span><span class="special">,</span> <span class="identifier">Context</span> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span></pre></div>
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<a name="id-1.3.32.5.58.4.4"></a><h2>Description</h2>
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<a name="id-1.3.32.5.58.4.4.2"></a><h3>
<a name="id-1_3_32_5_56_2_1_1_1_3-bb"></a><code class="computeroutput">null_eval</code> public member functions</h3>
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<pre class="literallayout"><span class="keyword">void</span> <a name="id-1_3_32_5_56_2_1_1_1_3_1-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">Expr</span> <span class="special">&amp;</span> expr<span class="special">,</span> <span class="identifier">Context</span> <span class="special">&amp;</span> context<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
<p>
                  For <code class="computeroutput">N</code> in <code class="computeroutput">[0,Expr arity)</code>,
                  evaluate:
                  </p>
<pre class="programlisting"><code class="computeroutput"><a class="link" href="../eval.html" title="Function eval">proto::eval</a></code>(<code class="computeroutput"><a class="link" href="../child_c.html" title="Function child_c">proto::child_c</a></code>&lt;N&gt;(expr), context)</pre>
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<div class="copyright-footer">Copyright © 2008 Eric Niebler<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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